A desirable characteristics of x-ray tubes for some applications, especially for portable x-ray sources, is small size. Due to very large voltages between a cathode and an anode of an x-ray tube, such as tens of kilovolts, it can be difficult to reduce x-ray tubes to a smaller size.
Another desirable characteristic of x-ray tubes is electron beam stability within the x-ray tube, including both positional stability and steady electron beam flux. A moving or wandering electron beam within the x-ray tube can result in instability or moving x-ray flux output. An unsteady electron beam flux can result in unsteady x-ray flux output.
Another desirable characteristic of x-ray tubes is a consistent and centered location where the electron beam hits the target, which can result in a more a consistent and centered location where x-rays hit a sample. Another desirable characteristic of x-ray tubes is efficient use of electrical power input to the x-ray source. Another desirable characteristic is high x-ray flux from a small x-ray source.